Research On Single-node WiFi Indoor Positioning Technology Based On CSI

With the rapid development and deployment of wireless networks and mobile Internet,people pay more and more attention to Location-based services(LBS).Global positioning systems(GPS),which can provide high-precision positioning outdoors.But't meet people's positioning needs because of the shelter of buildings.Therefore,it is of great practical significance to study a suitable indoor positioning system.Since WiFi devices are widely used,WiFi-based indoor positioning systems have advantages such as convenience,ease of deployment,and low cost,which has been a major indoor location technology.In recent years,Channel State Information(CSI)has been successfully extracted from commercial WiFi devices.Because CSI contains richer information than conventional RSSI,it is capable of achieving high-precision indoor positioning conditions.Research hotspots.Therefore,this article is based on the CSI indoor positioning technology,the main contents of the study are as follows:1.Propose an indoor positioning scheme based on the TR-MUSIC algorithm.The time-reversal(TR)algorithm has a spatial focusing effect.The channel impulse response(CIR)of each different geographical location is the only characteristic.The more obvious the characteristics of the multipath,the more CIR is collected as the characteristic.Create a fingerprint library.The super-resolution multi-signal classification algorithm(MUSIC)algorithm uses a smooth receiving matrix to achieve the single-node router's angle of arrival estimation.The algorithm also has a good effect in non-line-of-sight environments.Therefore,combined with the advantages of the arrival angle estimation method and the TR fingerprint positioning scheme,this paper innovatively uses the "ray-like" indoor sampling point partitioning scheme.The arrival angle information provided by the MUSIC algorithm can be used to reduce the positioning target to a smaller range.The fingerprint database is streamlined,reducing the number of fingerprint matching and improving the timeliness of positioning.2.In-depth analysis of signal processing errors in the WiFi receiver's signal processing to establish a linear phase error model and nonlinear phase error model for CSI.According to the phase error model,three linear phase error elimination algorithms and a nonlinear phase error algorithm are proposed.Using the collected data for simulation analysis,the correctness of the phase error elimination algorithm was proved.Finally,the system proposed in this paper adopts phase error elimination algorithm based on linear transformation to effectively improve the accuracy of positioning results.3.In-depth research and discussion based on TR indoor positioning system,for the current TR system needs to collect multiple channel CSI frequency hopping,using frequency band splicing to achieve high-precision indoor positioning;online positioning needs a large number of matching and the problem of large amount of calculation.This paper presents the TR-MUSIC algorithm and implements the single-channel multi-antenna TR algorithm to solve the problem of frequency hopping and high-bandwidth requirements.The use of clustering algorithm reduces the TR fingerprint library to reduce the amount of matching,while using the MUSIC algorithm to obtain the arrival angle to reduce the online.Match location calculations.The experiment proves that the positioning in a complex indoor environment is realized on a single commercial WiFi device,and the positioning and timeliness becomes better.4.Finally,the experiment is designed in a strong-vision laboratory and in a non-line-of-sight corridor.Arranging a single commercial WiFi device as a wireless AP,using the modified laptop as a mobile terminal,the TR-MUSIC algorithm can achieve a 96% positioning accuracy rate in a laboratory with a sampling interval of approximately 1m and a 0.5m sampling interval.At the same time,online positioning is a 60% reduction in fingerprint search matching time,which effectively enhances the timeliness of the positioning system.This can prove that the system satisfies the sub-meter indoor positioning requirements.